Improvements in the outcome for women with breast cancer will require an emerging new breed of investigator, the translational researcher. Scientists with a strong foundation in both basic molecular and cellular research who also have an understanding of the clinical disease will direct the most effective future of breast cancer research. Such investigators have been called "translational" because of their ability to translate basic findings into clinical strategies. This type of training requires both a well-funded core of investigators performing basic laboratory research, and an excellent clinical training program. At Baylor College of Medicine, the recently established Breast Center affords such a combination. In this application, by the third year, we propose to support 12 Ph.D. or M.D. postdoctoral trainees. All trainees will work on an aspect of breast cancer chosen from hormone action and therapeutic applications, growth factors, signal transduction, cell cycle control, normal breast development, breast cancer prevention, breast cancer evolution, molecular genetics, or gene therapy. Formal didactic courses covering scientific writing and research grants, biostatistics, problems in clinical breast cancer, and histopathology of breast cancer evolution will be required. Progress and direction of the trainee's research project will be closely monitored in bi-weekly data reviews. Trainees will also attend a weekly clinical breast cancer case conference in order to increase their understanding of clinical issues. Because of our integrative nature, and the balanced inclusion of M.D. and Ph.D. mentors, the trainees will have abundant opportunities to interact with their clinical counterparts for discussion of translational issues. Thus, by providing a program that involves laboratory training under the direction of well-established mentors with a long-standing track record of breast cancer research, interaction with successful physician-scientists, and exposure to clinical breast cancer issues, we will have created a unique opportunity to train new translational researchers.